Persistent Down-Beating Torsional Positional Nystagmus: Posterior Semicircular Canal Light Cupula?

Figure 1

Video-oculographic recording of torsional down-beating nystagmus in the supine position in the head roll test. The vertical component is observed to be down-beating (slow phase velocity 16.5°/s, 84 beats/min) on the vertical recording. The torsional component is observed as a horizontal component beating toward the left on the horizontal recording. Video-oculography was performed using the public domain software ImageJ and a Windows computer [10].